Of all the things riding on the match, Alex Song’s dignity in the dressing room was the least obvious. But his bet with Andre Santos proved to be the catalyst to produce one Arsenal’s all-time great assists and send Arsenal through to the knock-out stages.

Picking the ball up slightly to the left of Borussia Dortmund’s half – in a position Santos himself may have expected to have been – he went on a slaloming run down the touchline, taking on three men before delivering a pin-point cross onto the head of Robin van Persie. The goal came just after Dortmund had cranked up the pressure after the interval and Arsène Wenger was grateful to Alex Song for breaking free from the remits of his trade. “Song did something exceptional for a defensive midfielder,” he said after. Song, though, revealed it was a wager with Santos which inspired him but more tellingly, gave an insight to the strength of Arsenal’s dressing room at the moment. “What’s important is not what I did,” said Song. “It’s what the what team did tonight. We had a good result. Before the game, I said to André [Santos]: ‘Tonight I will score or I will give an assist,’ and he said: ‘No chance.’ It was that sort of challenge you give each other before a game.”

For Arsenal fans, Alex Song’s all action displays are nothing new and they feel he deserves greater recognition for his consistency in the holding role. Of course, that role has been made easier this season – as Jack Wilshere also did last season – because of the arrival of Mikel Arteta. Nonetheless, Song still rose to the occasion and in the second-half – after the whole team had been given an unrelenting test in the first – came up with a number of important blocks and interceptions. His glide means he doesn’t need to slide to win the ball back and because he stays on his feet, Arsenal are able to attack as soon as he makes a tackle. He made 5 in fact while also executing 7 interceptions, showing how important he is to the way Arsenal functions.

It’s a more functional Arsenal this season; sort of a halfway house between pragmatism and the romanticism of the past and it’s proving to be the perfect blend. Initially, though, the cautiousness of Arsenal’s approach play was exposed as Dortmund hounded them in possession. However, they were patient to ride through the storm, particularly in the first 15 minutes and their passing was excellent in the second-half. The tempo was increased while Dortmund tired after their excursions against Bayern Munich in the weekend, and Arsenal finished them off with the efficiency normally typical of German opponents. Commendably, Jurgen Klopp was unwilling to attribute the loss of Mario Gotze and Sven Bender through injury as turning points but it did massively impact on their strategy. Bender in particular, sets the tone for the high pressing to work, as he backs up the work of the forwards by aggressively getting tight to the opponent’s central midfielders. As a result, Arsenal suffered early on in that area.

Jurgen Klopp’s tactics must be commended; he has the look of a genius and his side buzzed around the pitch like the particles in the Hadron Collider. The 4-2-3-1 morphed into a 4-4-2 off the ball and the wall of pressure they created stopped Arsenal from passing it through the centre. Ultimately though, both sides wanted to play through the wings; Dortmund were threatening at first but Arsenal’s defending around the box continues to impress. Wenger’s side, however, remained patient and they knew if they were able to get the ball to Walcott and Gervinho, they had every chance of exposing Dortmund’s impetuousness off the ball. The big difference between the two attacks, though, turned out to be van Persie and there was no doubt he was going to get the goals. Klopp promised to stop the striker by stopping the supply to him but the nature of van Persie’s play was an altogether unfamiliar threat. In the end, Klopp’s words seemed to resonate the same mixed feeling of awe and resignation that van Persie has inflicted on his opponents in his amazing run. “But Robin van Persie, wow, what a performance, what a player,” said Klopp. “He’s certainly one of the best in Europe. I’ve hardly ever seen a player who plays so deep in midfield and then is such a danger in the box.”

Some Chalkboards…..

1. Dortmund’s pressing

Borussia Dortmund’s pressing in the first 15-30 mins will have been familiar to Arsenal fans in more ways than one. While it has drawn comparisons with Barcelona’s rapid spell of pressure at the Emirates in 2009, it more closely resembles Arsenal’s efforts which worked so successfully for two-thirds of last season. Shinji Kagawa presses alongside Robert Lewandowski to make a 4-4-2 when closing down – similar to what Cesc Fábregas had been doing – and behind them was a unit who defended through “through-marking;” (i.e. by getting tight to stop the passes from reaching their targets). Sven Bender did that particularly well and as such, his removal from the game, from a defensive viewpoint, can be seen as a turning point. Dortmund created a first line of pressure that stopped Arsenal from passing the ball into the centre of midfield.

Arsenal had their own strategy to evade the press and as a result, perhaps they didn’t mind the fact the middle was blocked. Arteta and Song pushed up instead of dropping deep to pick up the ball therefore affording the centre-backs more room in the build up. Arsenal had plenty of ball in their own half but struggled to unsettle Dortmund’s pressing. It was not until the second-half when Arsenal passed the ball quicker that Dortmund’s pressing became less effective.

The teams close us down so much high up because they know we play through the middle,” said the manager last season. “I push my midfielders a bit up at the start to give us more room to build up the game. When you come to the ball we are always under pressure, so Song is a bit naturally high up because I want him high up. I am comfortable with that sometimes it leaves us open in the middle of the park. We want to play in the other half of the pitch and, therefore, we have to push our opponents back. But my philosophy is not to be in trouble, but to fool the opponent into trouble.”

Only 22% of Arsenal’s play came through the middle due to Dortmund’s pressing and compactness. Their season average through the middle is 34%.

2. Arsenal’s defensive plan

Alex Flynn, the author of Arsènal: The Making of a Modern Superclub, said on twitter that “Arsène Wenger has no defensive plan B.” Which is quite an oversight from someone who has “analysed” Arsenal extensively during Wenger’s reign because it is quite evident he has changed his defensive strategy this season, and has done over the last few years. The change sees Arsenal dropping into their own half instead of aggressively searching for the ball and their improvement has become more noticeable as the season has progressed. Initially, they failed to get to grips with it but their defensive security has gradually improved and their defending around the box – bar the mistake at the end – is now more solid.

In Arsenal’s first European match last season, they pressed more aggressively and won the ball back higher up the pitch. As such, it echoes Dortmund’s tactics last night and highlights the marked difference in Wenger’s defensive plan this season.

3. Explosive Gunners

Jurgen Klopp bemoaned the lack of directness in Dortmund’s attacking play and that can be shown by the amount of times they attempted to take an Arsenal defender on. Without the magical feet of Götze, Dortmund lacked dynamism on the wings. Arsenal in comparison have plenty although they were far more successful on the less clogged left-hand side. Both sides, however, attempted the same amount of crosses at fourteen each.

4. The joy of Robin van Persie

What’s even more impressive about Robin van Persie is that he runs so much – as much as midfielder would. Last night, he covered 11252 metres – the 2nd highest for Arsenal. I watch him and think “Arsenal don’t press that intensely yet his figures so high. Why is that?” And that’s because he works so hard to get back into position when the team defends, acting as the reference point while his movement off the ball is stunning, always working the central defenders. Klopp says he’s rarely ever encountered a player like him and in the second-half, once Arsenal took the lead, van Persie used his intelligence to move around the pitch and allow the faster Theo Walcott and Gervinho to profit on the break.